Regensburg 2004 – scientific programme

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DS: Dünne Schichten

DS 22: Postersitzung

DS 22.36: Poster

Tuesday, March 9, 2004, 14:30–17:00, Poster B

TEM Investigation of the Structure and Geometry of Nanotunnels formed upon Cu Deposition on VSe₂ Surfaces — •E. Spiecker, S. Hollensteiner, and W. Jäger — Technische Fakultät der Christian-Albrechts-Universität zu Kiel

Linear nanostructures formed in the early stages of Cu deposition onto VSe₂ crystal surfaces have been studied in detail by TEM in plan-view geometry. The nanostructures are found to be made up of two parallel strands each of them consisting of a linear array of VSe₂ platelets. Combining diffraction analyses with tilt experiments the platelets of the two strands are shown to be symmetrically inclined by ∼ 30^o with respect to the surface, thus forming a roof-like nanotunnel with triangular cross-section. Along the strands the platelets show only minor misorientations with respect to each other. No gaps are observed at the substrate-platelet interfaces and at the interfaces along the ridges. The symmetry of the configuration and the sharpness of these interfaces indicate the presence of linear structure modifications with lateral dimensions of only few nanometers. These structures might be composed of special structural units, such as the topological defects discussed for caps of MoS₂ nanotubes. Our observations of the presence of substrate dislocations which are spatially correlated with the nanoroofs indicate that the nanoroof formation is connected with dislocation injection, thus providing a mechanism for strain relaxation during the early deposition stages. A formation model will be presented which extends earlier suggestions attributing the formation of nanotunnels to the relaxation of compressive surface strain.